This invention relates to continuous rainwater monitoring devices, which are capable of continuous quantitative evaluation of the contents, such as hydrogen ions and other ionic substances, etc., contained in the rainwater.
In recent years, acid rain has become a world wide problem, on account of their adverse effects on forests and lakes, and further, on flora and fauna thereof.
A device as shown in FIG. 1 has been known as a rainwater monitoring device for the measurement of the pH values of the rainwater, and is utilized for the purpose of investigating and researching the problem of acid rain. The device of FIG. 1 comprises the following: a funnel-shaped water receiver 101 for receiving the rainwater; a reservoir 102 disposed thereunder for storing the rainwater collected by the receiver; and a pH sensor 103 for analysing the pH value of the rainwater stored in the reservoir 102. The receiver 101 and the reservoir 102 are placed outdoors during rainfalls for sampling the rainwater. The rainwater thus sampled is supplied to the pH sensor 103 as the specimen material for the measurement of the pH value of the rainwater. After the measurement is made, the water receiver 101 and the reservoir 102 are cleaned manually.
The above-described conventional rainwater monitoring device has the following disadvantages. Since the measurements, as well as the cleaning operations after the measurements, are all effected manually by personnel, the device not only incurs personnel expenses, but has the problems that the cleaning of the measurement containers such as the receiver 101 and the reservoir 102 tend to be insufficient, and errors in the measured values tend to be great due to variations in the cleanliness of the reservoir 102 and the receiver 101 after they are cleaned. Namely, for measurements of extremely high precision, thorough cleaning of the measurement containers for the rainwater is essential. To this end, it is necesary to effect exact evaluations of the cleaning operations of the measurement containers after the cleaning. For effecting such exact cleaning evaluations, it is necessary to clean under identical conditions the measurement containers for the rainwater on the one hand, and the evaluation containers for the cleaning water on the other, which are for evaluating the contamination states of the cleaning water that has been used in cleaning the measurement containers for the rainwater. When, however, the cleaning is effected manually, it is extremely difficult to control the cleaning conditions to be exact as is required. Thus, cleaning evaluations may be completely omitted, or, even when cleaning evaluations are effected, they tend to be far from sufficient since the cleaning conditions as mentioned above are not controlled exactly.
Recently, the need for taking preventive measures against acid rains and for suppressing occurences of acid rains are becoming increasingly apparent. For effecting these, it is necessary to analyse the ionic contents, ect., of the rainwater for the purpose of investigating and determining the rainfall regions of the acid rains or the frequencies thereof, so that the sources of release of contaminants can be specified on the basis of the analyses. For such analysis, it is necessary to enhance the measurement sensitivity such that trace amounts of ions at the level of a few ppb (parts per billion) to a few hundred ppb can be detected; however, the above conventional rainwater monitoring device falls far short of meeting such requirements.